You can find the most eye-opening things online. So why don't you?

It's a big, wide world out there – not that you'd know it from your Facebook feed. Photograph: HO/AFP/Getty Images

Snappy buzz-phrases identifying purported new social trends get invented, it seems, at the rate of about a hundred per week, and most of them are worthless. But a phrase coined by the media scholar Ethan Zuckerman jolted me out of my jargon-jadedness the other day. You see, I think I may be guilty of "imaginary cosmopolitanism".

Zuckerman invented the term to describe a certain kind of online behaviour. But the offline archetype of the imaginary cosmopolitan is the person who feels proud to live in a diverse city or neighbourhood – while being forced to concede that his or her actual social circle is suspiciously full of people of the same ethnicity, social class or age range. (Does this describe you? Me too.) On the web, Zuckerman argues in his recent book Rewire: Digital Cosmopolitans In The Age Of Connection, this phenomenon is amplified. We feel connected to distant corners of the globe – which makes it easier to ignore the fact that what we actually spend our time doing is chatting to the same kinds of people about the same kinds of stuff.

In this excellent Point of Inquiry podcast, Zuckerman, who co-founded the blog network Global Voices, describes what happened when he measured his own online consumption, using the Mac app RescueTime: "I think of myself as a pretty global guy; I'm on the boards of a bunch of international organisations… [but] I spend a lot of my time reading Reddit. And I spend a lot of my time reading about the Green Bay Packers."

There's a longstanding debate about how far the internet serves to expose us to a diversity of viewpoints or functions, instead, as an echo chamber. But Zuckerman's insight is that the two might be intimately connected. If you're comfortable spending your online life in an echo chamber, maybe it's because you believe you're sampling a much wider range of opinion and perspective. "We need to ask whether we're reading the Times of India," Zuckerman writes, "or imagining that we are simply because we could be."

When Amazon recommends a book, or Facebook recommends a potential friend, you're benefiting from "collaborative filtering" – algorithms based on the assumption that you'll be interested in whatever those similar to you have already shown an interest in. Unfortunately, this only exacerbates homophily, our deep tendency to spend time with, and focus attention on, the people most like us. Using the web this way is a reliable route to getting the information you want. But Zuckerman argues that you may be missing the information you need – especially in an era when so many major challenges and opportunities are global in nature.

He suggests a number of interim fixes for addressing your own imaginary cosmopolitanism. You could track your own web use using RescueTime; you could examine possible gender bias in your Twitter habits with services like Twee-q; and you can follow the kinds of people Zuckerman calls "xenophiles" or "bridge figures" – culture-crossing homophily-destroyers such as the Kenya-born former US Marine Erik Hersman, or the media and technology writers Ahmad Humeid or Zeynep Tufekci.

But most of all, I like the sound of the hypothetical pro-serendipity recommendation engine Zuckerman proposes in the podcast:

Can we find you someone who has partial overlap with you, but who is different in some very specific ways? If I were building an algorithm like this, I might say 'Hey, here's someone who tweeted five of the same URLs that you did this week, but this person's from Nigeria, and may have access to a very different social circle.

Somebody build this, please! Oh, and meanwhile, if this blog post is the kind of thing you usually read on the web, why don't you take a moment to go and read something different instead?